What is the proper way to use an apostrophe?

Like, how?

>>17123693
When addressing a persons name, belongings, ect

>>17123665
Possessive- this is carl's
Combo words - it's = it is

I still get its and it's confused.

>>17123875
I pause (too often) and substitute "it is" in a sentence to see which to use.

For possessives, all have apostrophe s ('s), except for plurals already know being in s, in which case the apostrophe hangs out on its own.

Dave's sock
Children's socks
Families' socks